/*
 * Copyright (c) 2004 World Wide Web Consortium,
 *
 * (Massachusetts Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. This
 * work is distributed under the W3C(r) Software License [1] in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */
using org.w3c.dom;

namespace org.w3c.dom.ls
{

    /**
     *  <code>LSParserFilter</code>s provide applications the ability to examine 
     * nodes as they are being constructed while parsing. As each node is 
     * examined, it may be modified or removed, or the entire parse may be 
     * terminated early. 
     * <p> At the time any of the filter methods are called by the parser, the 
     * owner Document and DOMImplementation objects exist and are accessible. 
     * The document element is never passed to the <code>LSParserFilter</code> 
     * methods, i.e. it is not possible to filter out the document element. 
     * <code>Document</code>, <code>DocumentType</code>, <code>Notation</code>, 
     * <code>Entity</code>, and <code>Attr</code> nodes are never passed to the 
     * <code>acceptNode</code> method on the filter. The child nodes of an 
     * <code>EntityReference</code> node are passed to the filter if the 
     * parameter "<a href='http://www.w3.org/TR/DOM-Level-3-Core/core.html#parameter-entities'>
     * entities</a>" is set to <code>false</code>. Note that, as described by the parameter "<a href='http://www.w3.org/TR/DOM-Level-3-Core/core.html#parameter-entities'>
     * entities</a>", unexpanded entity reference nodes are never discarded and are always 
     * passed to the filter. 
     * <p> All validity checking while parsing a document occurs on the source 
     * document as it appears on the input stream, not on the DOM document as it 
     * is built in memory. With filters, the document in memory may be a subset 
     * of the document on the stream, and its validity may have been affected by 
     * the filtering. 
     * <p> All default attributes must be present on elements when the elements 
     * are passed to the filter methods. All other default content must be 
     * passed to the filter methods. 
     * <p> DOM applications must not raise exceptions in a filter. The effect of 
     * throwing exceptions from a filter is DOM implementation dependent. 
     * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-LS-20040407'>Document Object Model (DOM) Level 3 Load
    and Save Specification</a>.
     */
    public interface LSParserFilter
    {
        /**
         *  The parser will call this method after each <code>Element</code> start 
         * tag has been scanned, but before the remainder of the 
         * <code>Element</code> is processed. The intent is to allow the 
         * element, including any children, to be efficiently skipped. Note that 
         * only element nodes are passed to the <code>startElement</code> 
         * function. 
         * <br>The element node passed to <code>startElement</code> for filtering 
         * will include all of the Element's attributes, but none of the 
         * children nodes. The Element may not yet be in place in the document 
         * being constructed (it may not have a parent node.) 
         * <br>A <code>startElement</code> filter function may access or change 
         * the attributes for the Element. Changing Namespace declarations will 
         * have no effect on namespace resolution by the parser.
         * <br>For efficiency, the Element node passed to the filter may not be 
         * the same one as is actually placed in the tree if the node is 
         * accepted. And the actual node (node object identity) may be reused 
         * during the process of reading in and filtering a document.
         * @param elementArg The newly encountered element. At the time this 
         *   method is called, the element is incomplete - it will have its 
         *   attributes, but no children. 
         * @return 
         * <ul>
         * <li> <code>FILTER_ACCEPT</code> if the <code>Element</code> should 
         *   be included in the DOM document being built. 
         * </li>
         * <li> 
         *   <code>FILTER_REJECT</code> if the <code>Element</code> and all of 
         *   its children should be rejected. 
         * </li>
         * <li> <code>FILTER_SKIP</code> if the 
         *   <code>Element</code> should be skipped. All of its children are 
         *   inserted in place of the skipped <code>Element</code> node. 
         * </li>
         * <li> 
         *   <code>FILTER_INTERRUPT</code> if the filter wants to stop the 
         *   processing of the document. Interrupting the processing of the 
         *   document does no longer guarantee that the resulting DOM tree is 
         *   XML well-formed. The <code>Element</code> is rejected. 
         * </li>
         * </ul> Returning 
         *   any other values will result in unspecified behavior. 
         */
        short startElement(Element elementArg);

        /**
         * This method will be called by the parser at the completion of the 
         * parsing of each node. The node and all of its descendants will exist 
         * and be complete. The parent node will also exist, although it may be 
         * incomplete, i.e. it may have additional children that have not yet 
         * been parsed. Attribute nodes are never passed to this function.
         * <br>From within this method, the new node may be freely modified - 
         * children may be added or removed, text nodes modified, etc. The state 
         * of the rest of the document outside this node is not defined, and the 
         * affect of any attempt to navigate to, or to modify any other part of 
         * the document is undefined. 
         * <br>For validating parsers, the checks are made on the original 
         * document, before any modification by the filter. No validity checks 
         * are made on any document modifications made by the filter.
         * <br>If this new node is rejected, the parser might reuse the new node 
         * and any of its descendants.
         * @param nodeArg The newly constructed element. At the time this method 
         *   is called, the element is complete - it has all of its children 
         *   (and their children, recursively) and attributes, and is attached 
         *   as a child to its parent. 
         * @return 
         * <ul>
         * <li> <code>FILTER_ACCEPT</code> if this <code>Node</code> should 
         *   be included in the DOM document being built. 
         * </li>
         * <li> 
         *   <code>FILTER_REJECT</code> if the <code>Node</code> and all of its 
         *   children should be rejected. 
         * </li>
         * <li> <code>FILTER_SKIP</code> if the 
         *   <code>Node</code> should be skipped and the <code>Node</code> 
         *   should be replaced by all the children of the <code>Node</code>. 
         * </li>
         * <li> 
         *   <code>FILTER_INTERRUPT</code> if the filter wants to stop the 
         *   processing of the document. Interrupting the processing of the 
         *   document does no longer guarantee that the resulting DOM tree is 
         *   XML well-formed. The <code>Node</code> is accepted and will be the 
         *   last completely parsed node. 
         * </li>
         * </ul>
         */
        short acceptNode(Node nodeArg);

        /**
         *  Tells the <code>LSParser</code> what types of nodes to show to the 
         * method <code>LSParserFilter.acceptNode</code>. If a node is not shown 
         * to the filter using this attribute, it is automatically included in 
         * the DOM document being built. See <code>NodeFilter</code> for 
         * definition of the constants. The constants <code>SHOW_ATTRIBUTE</code>
         * , <code>SHOW_DOCUMENT</code>, <code>SHOW_DOCUMENT_TYPE</code>, 
         * <code>SHOW_NOTATION</code>, <code>SHOW_ENTITY</code>, and 
         * <code>SHOW_DOCUMENT_FRAGMENT</code> are meaningless here. Those nodes 
         * will never be passed to <code>LSParserFilter.acceptNode</code>. 
         * <br> The constants used here are defined in [<a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>DOM Level 2 Traversal and      Range</a>]
         * . 
         */
        int getWhatToShow();

    }
    public sealed class LSParserFilterConstants
    {
        // Constants returned by startElement and acceptNode
        /**
         * Accept the node.
         */
        public static readonly short FILTER_ACCEPT = 1;
        /**
         * Reject the node and its children.
         */
        public static readonly short FILTER_REJECT = 2;
        /**
         * Skip this single node. The children of this node will still be 
         * considered. 
         */
        public static readonly short FILTER_SKIP = 3;
        /**
         *  Interrupt the normal processing of the document. 
         */
        public static readonly short FILTER_INTERRUPT = 4;


    }
}